Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with paper liners or grease the muffin cups well.
In a large mixing bowl, whisk together the almond flour, baking powder, salt, and erythritol.
In a separate bowl, whisk the eggs, melted coconut oil (or butter), almond milk, and vanilla extract until fully combined.
Slowly pour the wet ingredients into the dry ingredients, stirring until a thick batter forms. Do not over mix.
Gently fold in the blueberries. If using frozen blueberries, you can coat them lightly with almond flour before adding to the batter to prevent them from sinking to the bottom.
Divide the batter evenly among the 12 muffin cups.
Bake for 20-25 minutes, or until the tops of the muffins are golden brown and a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.